Scopus İndeksli Yayınlar Koleksiyonu / Scopus Indexed Publications Collection

Permanent URI for this collectionhttps://hdl.handle.net/11147/7148

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Author: search.filters.author.Kiper, GokhanHas files: Yes

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Now showing 1 - 9 of 9
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Reconfigurable Polyhedral Mechanisms Using Scissor-Like Elements with Cantellation Transformation Between Dual Geometries
    (Pergamon-Elsevier Science Ltd, 2025) Liao, Yuan; Kiper, Gokhan; Krishnan, Sudarshan
    Deployable polyhedron mechanisms (DPMs) have garnered significant interest in architecture, aerospace, and robotics, where reconfigurable and space-efficient structures are crucial. This paper presents a tangential design method for DPMs using scissor-like elements (SLEs). Scissor units are placed along the edges of an equilateral polyhedron, tangential to its midsphere. This method enables the mechanisms to transform between a polyhedron and its dual, following the cantellation operation. Using screw theory, the kinematic properties of these mechanisms are analyzed. Results show that the DPMs exhibit 1-degree of freedom (DOF) under normal conditions and gain additional DOFs at multifurcation points, allowing for reconfigurable motion modes. Physical models based on various geometries, including Platonic, Archimedean, Johnson, and Catalan solids, help to validate the method's feasibility. Observations indicate that this method is only applicable to equilateral supporting polyhedra. The transformability and reconfigurability observed in these mechanisms demonstrate the potential of this approach for applications in architecture, aerospace, and robotics.
  • Article
    Citation - WoS: 1
    Citation - Scopus: 1
    Design Alternatives of Light Shelves Using Altmann Linkage
    (Solarlits, 2024) Atarer, Fulya; Korkmaz, Koray; Kiper, Gokhan
    This paper proposes a novel new light shelf design with Altmann linkage using its kinetic principles: geometry and rotational angles. As previous studies explain a light shelf's design in two ways: static and movable, the proposed one in this study has the potential to track the path of the sun due to its diagonal movement. The primary purpose is to direct the light shelf to intermediate directions, such as southeast and southwest, by utilizing the geometric properties of the Altmann linkage. The study explains how to dimension the links, calculate rotation angles, and model this device in Relux to test its daylight performance on specific dates in a year. A total of nine variations were analyzed during the three phases of design. They include shelf forms such as a rectangle, two rectangles, two squares, and varying link lengths, which define the distance to the windowsill. The final set of variations with two-square forms moving west and east successfully satisfied with sDA values as 71.52%, 72.99% (w), 75.92% (e); with ASE values as 8.83%, 8.56% (w), and 8.22% (e). This best design of Altmann linkage would be beneficial as an adaptive fa & ccedil;ade module that can direct daylight inside and achieve proper shading throughout the day and year. (c) 2024 The Author(s). Published by solarlits.com. This is an open access article under the CC BY license (https://creativecommons.org/licenses/by/4.0/).
  • Article
    Citation - WoS: 2
    Citation - Scopus: 2
    Function Generation With Planar Four-Bar Mechanisms as a Mixed Problem of Correlation of Crank Angles and Dead Center Design
    (Springer india, 2024) Kadak, Tarik; Kiper, Gokhan
    Function generation synthesis of mechanisms can be considered as the design of correlation of crank angles and dead dead-center position design. These two problems have been clearly defined and solved separately. But some problems may require both correlation of crank angles and dead dead-center design at different configurations. Such problems are called mixed function generation problems. In this paper, an overview of these mixed function generation problems for the planar four-bar mechanism are given and the problems are solved analytically or semi-analytically. Except three of them, all presented mixed function generation problem formulations are novel. The solutions of all problems including three positions for the four-bar mechanism and the solution of a problem including four positions for a four-bar mechanism are addressed. All problems are first reduced to a univariate equation and a fast solution is found. Thus, link lengths can be found quickly by changing the problem definition problems, and several design iterations can be performed in a short time. Numerical solutions of all problems have been demonstrated using Excel.
  • Article
    Citation - WoS: 12
    Citation - Scopus: 13
    Mobility Analysis of Tripod Scissor Structures Using Screw Theory
    (Pergamon-elsevier Science Ltd, 2024) Liao, Yuan; Kiper, Gokhan; Krishnan, Sudarshan
    Mechanisms consisting of spatial scissor units have different kinematic behaviors than those of planar scissors. However, their kinematics, especially the mobility analysis, has not received enough attention. Two types of deployable asseblies are analyzed in this paper, namely the translational and mirrored assemblies. Both the assemblies are made of tripod scissor units, and their instantaneous mobility are examined using screw theory. The study starts on the configuration where all the members have the identical deployment angle. Firstly, the geometric property of each assembly was studied. Then, screw-loop equations were developed based on graph theory and closure equations. Finally, the mobility of each assembly was computed using linear algebra. Following the analysis, physical prototypes were constructed to validate the results, and several different motion modes were obtained for the translational assembly. The analysis reveals different kinematic behaviors of the two assemblies. In the given configuration, the translational assemblies have four instantaneous degrees of freedom, while the mirrored assemblies have only a single instantaneous degree of freedom.
  • Conference Object
    Citation - WoS: 2
    Citation - Scopus: 2
    Function Generation Synthesis of Planar Slider-Crank Linkages for Given 3 Positions and a Dead-Center Position
    (Springer Verlag, 2020) Kiper, Gokhan; Gorgulu, Ibrahimcan; Kucukoglu, Sefa Furkan
    Function generation for finitely many positions and dead-center design problems are generally separately handled in the literature. This paper presents a mixed formulation for planar slider-crank linkages where three precision points and a folded or extended dead-center position are to be satisfied. The formulation results in an 8th degree univariate. Examples show that generally there are four real solutions, only two of which result in distinct solutions.
  • Conference Object
    Design of a Cable-Driven Four-Bar Mechanism for Arm Rehabilitation
    (Springer Verlag, 2017) Eraz, Talha; Kiper, Gokhan
    This paper presents the design of an assistive mechanism to be used for the rehabilitation of human arm. First the motions of two types of rehabilitation exercises are described. The motions are planar motions, so a planar four bar mechanism is designed. The synthesis problem is formulated as a three-position synthesis problem. Next, the actuation issue is addressed. Actuation via cables is preferred for better force transmission. The connection point of the cable to the mechanism is optimized considering the curvature of the coupler point curve. Finally, multiple pulleys are designed for enhancing force transmission.
  • Conference Object
    Path Generation Synthesis of Planar Double-Slider Linkages Via the Elliptic Coupler Curve
    (Springer Verlag, 2017) Kiper, Gokhan; Akbalcik, Almina; Sen, Zehra Betul
    The path generation synthesis of a double-slider linkage is performed for a given elliptic curve. It is shown that there are infinity(2) linkages that can trace the same ellipse. The formulation for obtaining all such linkages is presented. The formulation sheds light for the design of the planar slider-crank and four-bar linkages from the given algebraic form of the coupler path curve as well.
  • Conference Object
    Citation - WoS: 1
    Citation - Scopus: 1
    Alternating Error Effects on Decomposition Method in Function Generation Synthesis
    (Springer Verlag, 2017) Maaroof, Omar W.; Dede, Mehmet Ismet Can; Kiper, Gokhan
    In approximate function generation synthesis methods, error between the desired function's output and designed mechanism's output oscillate about zero error while crossing the zero error margin at precision points. The common goal of these methods is to minimize the error within the selected working region of the mechanism. For mechanisms like Bennett overconstrained six-revolute jointed linkages that have relatively large number of construction parameters, it is a difficult task to solve for them at once. Decomposition method enables to divide such linkages into two loops and independently solve for each loop with less construction parameters. Although some approximation methods are proven to produce smaller errors than others for a single-loop synthesis, in this work, it is shown that smaller errors are not guaranteed for a certain method when used along with decomposition method. Numerical examples indicate that in decomposition method, more attention should be given to the alternation of the error of each decomposed mechanism, rather than the approximation method used.
  • Conference Object
    Citation - WoS: 2
    Citation - Scopus: 5
    Computing the SafeWorking Zone of a 3-RRS Parallel Manipulator
    (Springer Verlag, 2017) Patel, Dhruvesh; Kalla, Rohit; Tetik, Halil; Kiper, Gokhan; Bandyopadhyay, Sandipan
    Determination of the safe working zone (SWZ) of a parallel manipulator is a one-time computational task with several permanent benefits. As this sub-space of the workspace of the manipulator is free of both the loss- and gain-type singularities, link interference, as well as physical joint limits, the manipulator can move freely in this space. Moreover, if the natural choice of a convex-shaped SWZ is adhered to, then point-to-point path planning inside the SWZ always has a trivial solution, namely, a segment joining the two points, which is guaranteed to be inside the workspace. In this paper, the SWZ of the 3-RRS existing in the Izmir Institute of Technology has been computed. Starting with the geometry of the manipulator, the loop-closure constraint equations have been derived. The singularity conditions are obtained based on the singularity of certain Jacobian matrices associated with the constraint functions. The interference between the links are detected by first encapsulating the links in rectangular parallelepipeds, which are then discretized into triangles, and subjected to collision tests between the relevant pairs of triangles. Using these theoretical developments, the SWZ is computed. The numerical results are depicted graphically.